Currently I am playing tanker in jpn server. Sometimes I met some new player who new to dungeon. So I just write down what I think is important.

All DPS : NEVER start attack bfore tanker. Attack only after tanker lure the monster. Some japanese tanker will use mark,so please just attack monster with mark.

Arcanist: Change the pet to Obey mode（セミオート）. Some player use tank type(yellow) but caster-type(Blue) is better....

Lancer/Pugilist: Don't forget to use LimitBreak.

Healer: Don't use medica too often or monsters will go after healer. And don't forget to off Cleric Stance when using cure.